Method of extruding multiple continuous bodies of radially-layered product

ABSTRACT

A multiple-orifice extrusion manifold  10  is disclosed which includes a first housing  20  defining an outer chamber  170  and an extrusion wall  140 . A plurality of orifices  80 , adapted for extruding a first substance from the outer chamber  170 , extend through the extrusion wall  140 . An inlet pipe  40  is provided in the first housing  20  for flowing the first substance into the outer chamber  170 . The inlet pipe  40  is located so as to permit flow of the first substance symmetrically within the outer chamber  170 . A second housing  190  which defines an inner chamber  200  is provided within the first housing  20 . The second housing  190  is located symmetrically within the outer chamber. A plurality of tubes  210  extend from the second housing  190 . Each tube  210  has a first end  212  opening into the inner chamber  200  and a second open end  213  cooperatively aligned with an orifice  80  for extruding a second substance from the inner chamber  200  through the tube  210  and to within the first substance. Thus, each extrudate substance is flowed to an extrusion orifice  80  through a flow path, which is symmetrical with all other flow paths for that substance. The manifold housing  20  presents a right circular cylindrical outer surface  70  with the extrusion orifices  80  therein. The orifices  80  are equally spaced around the outer surface  70 . Three blades  110  with a cylindrically rotating path about the cylindrical outer surface  70  are provided to cut a continuous extrusion at each orifice as the blade or blades pass the orifice. The blades  110  are mounted for rotation around the inlet pipe  40  which supplies an extrudable substance to the housing.

PRIORITY CLAIM

This Application is a divisional of application Ser. No. 09/231,474filed Jan. 14, 1999 (now U.S. Pat. No. 6,206,678), which is a divisionalof application Ser. No. 08/166,390, filed Dec. 13, 1993 (now U.S. Pat.No. 5,906,838 issued May 25, 1999), upon which a claim of priority isbased.

DESCRIPTION

1. Technical Field

The present invention relates generally to a method and apparatus forextruding generally cylindrical, multi-layered materials and moreparticularly to a manifold with multiple-extrusion orifices forcoextrusion, such as may be used in the manufacture of center-filledfood products and methods of using the same.

2. Background of Invention

There are numerous desirable products made by extruding two or moresubstances together so that the substances become generallyradially-layered. The process for making such products is generallyreferred to as coextrusion. In other words, a product is formed byextruding a first substance which circumferentially surrounds a secondsubstance and, where desired, the second surrounds a third, and so on.Others have proposed methods and apparatus for making such products. Forexample, U.S. Pat. Nos. 4,402,898 and 4,208,175 disclose methods andapparatus for extruding radially layered plastic tubing. U.S. Pat. Nos.5,124,161; 5,120,554; 5,110,276; 4,900,572; 4,882,185; and, 4,648,821disclose methods and apparatus for extruding center-filled foodproducts.

Generally coextrusion involves a separate extruder for each substance tobe combined into the multi-layered extrusion product. Each of theseextruders flows the extrudable substance or “extrudate” into anapparatus such as a manifold. This apparatus presents flow paths to thevarious substances to direct them ultimately to a means which combinesthem and extrudes them as a multi-layered (usually radially-layered)product through an extrusion orifice. While not disclosed by some,others in the art cited above recognize a need for the apparatus ormanifold to have multiple extrusion orifices for higher productionoutput.

However, problems arise in connection with producing radially-layeredproducts, especially when multiple orifices are employed. For example,it can be difficult to achieve a product which is uniform from orificeto orifice. A primary reason for this is that the extrudable substanceflowing from any given extruder must be divided in some manner todistribute the substance along a flow path to each extrusion orifice.With conventional apparatus, achieving uniform distribution to eachorifice, requires separate adjustment to vary the flow path or flow rateleading to each given orifice. Such adjustments must be checked, andperhaps repeated whenever a new batch of extrudate is supplied from theextruder. Adjustments may also be required upon conditions changing,such as temperature or flow rate from the extruder. These adjustmentsare not desirable as they require the purchase, installation andmaintenance of the flow varying apparatus. Also, valuable productiontime is consumed in making the adjustments and scrap may be generateduntil the adjustments are complete. For example, U.S. Pat. Nos.5,120,554 and 5,110,276 teach the use of valves interposed in the flowpath of the extrudates to vary and adjust volumetric flow.

Uniform distribution of extrudate is also impeded by the inherentnecessity of introducing the flow path of inner extrudable substanceswithin the flow path of the outer extrudable substances. To address thisproblem, others have proposed complex manifold structures employingspider plates and the like which attempt to uniformly divide outersubstance by flowing into additional flow paths temporarily while theflow path of the inner substance can be interposed and brought intocoaxial alignment, with the outer substance flow path. In theseembodiments, the outer substance is generally then recombined before itproceeds to the extrusion orifice. The apparatus proposed for thisdividing and recombining flow is complex and further impedes uniformdistribution. The complexity also increases equipment capital andmaintenance costs. Examples of these structures are disclosed in theabove-cited patents.

While presenting an improvement over the above discussed approaches andwhile enjoying significant commercial success, U.S. Pat. No. 4,900,572to Repholz nonetheless discloses, among other things, the need foradjustment of flow and distribution of extrusion. For example, inRepholz, the extrudate flow and uniformity are adjusted by separatelyturning individual eccentric sleeves in each of the extrusion orifices.

Generally uniform distribution of extrudable substance is alsofrustrated by non-symmetrical and nonequal flow paths presented byconventional apparatus from the extruders to each of the multiPleextrusion orifices.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for high volume,cost efficient extrusion of a generally radially-layered product.According to one aspect of the invention, a plurality of extruders areprovided and a flow path between an extruder and each of a plurality ofmultiple-extrusion orifices is sufficiently equal to obviate the needfor individual adjustment apparatus, such as valves or eccentric sleevesin the orifices, to obtain a substantially uniform distribution andvolumetric flow at each extrusion orifice. The use of symmetry in amultiple-orifice extrusion manifold is contemplated as another aspect ofthe invention. Thus, a plurality of radially-layered substances areproduced by providing an extrudable substance for each layer of product,extruding each extrudable substance to a plurality of extrusion orificesthrough an equal and symmetrical flow path.

More specifically, one aspect of the invention contemplates amultiple-orifice extrusion manifold including a housing with asymmetrical chamber and a plurality of orifices in the housing adaptedto extrude a first substance from the symmetrical chamber. The orificesare generally symmetrically spaced from each other. A plurality oftubes, adapted to carry a second substance, extend through the chamberin a generally symmetrical relationship to each other and thesymmetrical chamber. Each tube has a terminal end cooperatively alignedwith an extrusion orifice to extrude a second substance within the firstsubstance. Thus, each extrudate substance is flowed to an extrusionorifice through a flow path, which is symmetrical with all other flowpaths for that substance.

According to another aspect of the invention, a multiple-orificeextrusion manifold is employed, which includes a first housing definingan outer chamber and one or more extrusion walls. A plurality oforifices, adapted for extruding a first substance from the outerchamber, extend through the extrusion walls. An inlet is provided in thefirst housing for flowing the first substance into the outer chamber.The inlet is located so as to permit flow of the first substancesymmetrically within the outer chamber. A second housing which definesan inner chamber is provided within the first housing. The secondhousing is located symmetrically within the outer chamber. A pluralityof tubes extend from the second housing. Each tube has a first endopening into the inner chamber and a second open end cooperativelyaligned with an orifice for extruding a second substance from the innerchamber through the tube and to within the first substance.

According to another aspect of the invention, a multiple-orificeextrusion manifold includes a plurality of extrusion orifices and ameans for flowing an outer layer substance from a first extruder outputsymmetrically to the extrusion orifices. The means for flowing an outerlayer substance provides a fixed and equal flow path from the firstextruder output to each of the extrusion orifices. A means for flowingan inner layer substance from a second extruder output to the extrusionorifices is provided. The means for flowing an inner layer substancealso provides a fixed and equal flow path from the extruder output toeach of the extrusion orifices.

According to another aspect of the invention, a multiple-orifice,multiple-layer extrusion apparatus, which includes a plurality of meansfor combining a plurality of extrudable substances and for extrudingthem as a continuous, radially-layered, generally cylindrical body. Aplurality of extruders provide the plurality of extrudable substances. Aplurality of flow paths are provided for each extrudable substance. Theflow paths extend between the extruders and the means for combining aplurality of extrudable substances. Each of the flow paths for anextrudable substance is sufficiently symmetrical to the others, suchthat a flow of the extrudable substance is substantially equal at eachorifice.

Another aspect of the invention provides a multiple-extrusion manifoldhaving a first housing which defines an outer chamber and includes oneor more extrusion walls. A plurality of orifices extend through theextrusion walls and are adapted for extruding a first substance from theouter chamber. A second housing within the first housing defines aninner chamber having an axis. A plurality of tubes on the second housingeach have a first end opening into the inner chamber and a second endcooperatively aligned with an orifice for extruding a second substancefrom the inner chamber. Each of the tubes extends away from the innerchamber at an angle to the axis thereof.

Another aspect of the present invention provides that a multiple-orificeextrusion manifold has a housing which presents a right circularcylindrical outer surface with a plurality of extrusion orificestherein. Optionally, the orifices are equally spaced around the outersurface. The manifold may also include one or more blades with acylindrically rotating path about the cylindrical outer surface to cutthe continuous extrusion at each orifice as the blade or blades pass theorifice. The blades may uniquely be mounted for rotation around an inletpipe which supplies an extrudable substance to the housing.

Other advantages and aspects of the present invention will becomeapparent upon reading the following description of the drawings anddetailed description of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a multiple-orifice extrusion manifold inaccordance with the present invention;

FIG. 2 is a cross sectional view of the manifold of FIG. 1 taken alongline 2—2 of FIG. l;

FIG. 3 is an expanded, partial cross sectional view of the manifold ofFIG. 1; and,

FIG. 4 is an expanded, partial cross sectional view of an alternateembodiment of a multiple-extrusion manifold in accordance with thepresent invention.

DETAILED DESCRIPTION

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated.

Referring now to the drawings, FIG. 1 discloses a multiple-orificecoextrusion manifold 10. The manifold 10 is used to coextrudecenter-filled pet food products such as those described in U.S. Pat. No.4,900,572, the disclosure of which is incorporated herein by reference.While details of the extrudate ingredients can be found by reference tothe above-cited patent, it should, at least, be understood that theextrudable substances of the present embodiment are dissimilarlytextured extrudable doughs.

The manifold 10 includes a housing 20, inlet pipe 30, inlet pipe 40, anda cutting assembly 50, all of which are aligned along a commonlongitudinal axis. The manifold is secured by a mounting bracket 60. Inpractice, inlet pipe 40 will be attached to an output of a firstextruder (not shown) containing a first extrudable dough which willcomprise the outer layer of the pet food. Inlet pipe will be attached toan output of a second extruder (not shown) containing a secondextrudable dough which will comprise the inner layer or center of thecenter-filled pet food. Both inlet pipes 30 and 40 are attached toextruder feed pipes (not shown) by pipe threads 35 and 45 respectively.As will be understood by those in the art, the manifold 10 is of afree-standing type also referred to as a pipehead manifold. It should beappreciated, however, that the principles of the present invention mayalso be employed with an extrusion apparatus which is integral with anextruder.

Housing 20 of manifold 10 is generally cylindrical and presents acylindrical outer extrusion surface 70. Housing 20 has three extrusionorifices 80, (one of which is shown in FIG. 1) from which emanates threecontinuous bodies of coextruded pet food. The cutting assembly 50 cutsthe continuous bodies into desired product lengths.

The cutting assembly includes a hub 90, a flange 100 and blades 110. Asbest seen in FIG. 2, the hub 90 is rotatably mounted on the inlet pipe40 so as to rotate about the inlet pipe 40 on bearings 120. Flange 100is a circular plate attached to the hub with a diameter approximatingthat of a diameter of the extrusion surface 70 of housing 20. Blades 110are attached to a periphery of flange 100 at right angles thereto so asto extend over extrusion surface 70 sufficient to pass over extrusionorifices 80. The cutting assembly 50 is rotated by an external motordriving a “V-belt” which engages in pulley slot 121. Blades 110 aredetachably mounted by slot head screws 130 so that they can be easilyremoved for cleaning and sharpening. A distance of the blades 110 fromorifices 80, in other words, a blade clearance can be adjusted byplacing washers 131 under the head of screws 130.

The length of the finished product can be adjusted by the speed ofrotation of the cutting assembly 50, the number of blades 110 employedor the extrusion rate of the continuous body at the orifices. Forexample, the product will be longer if fewer blades 110 are used, or ifthe cutting assembly 50 rotates slower, or if the flow rate at theextrusion orifices 80 is faster. In practice, a sanitary shroud (notshown) is positioned around the housing to capture the individuallengths of pet food product and direct them downwardly to a conveyor forfurther processing in a manner disclosed in U.S. Pat. No. 4,900,572.

FIG. 2 discloses that housing 20 is generally formed by a cylindricalextrusion wall 140, and circular first and second end walls 150 and 160,respectively. The extrusion wall 140 and end walls 150,160 are boltedtogether and define an outer chamber 170. Outer chamber 170 is radiallysymmetrical about an axis which is coaxial with the longitudinal axes ofinlet pipes 30 and 40.

End wall 150 includes an opening 151 at its center to permitinterconnecting attachment of inlet pipe 30 to the chamber 170. End wall160 has an opening 161 at its center to permit interconnectingattachment of inlet pipe 40 to chamber 170.

Extrusion wall 140 includes three openings 180 extending therethrough.The openings are symmetrically spaced about a circumference of extrusionwall 140 and the axis of chamber 170. As best disclosed in FIG. 3, theopenings 180 are fitted with outer sleeves 181 and inner sleeves 182. Aninner end 183,184, respectively, of sleeves 181,182 are each tapered toform a frustoconical inner orifice opening 185. Sleeves 181 and 182 areright-circular cylinders, thus defining the cylindrical extrusionorifice 80. It should be understood that, if other than a circularcylindrically-shaped continuous product is desired, the sleeves 181,182can be replaced with sleeves which will define a different shapecylinder for the extruded continuous body. For example, sleeves may beprovided to extrude a continuous body which, when cut to product length,resemble a cut of meat, such as a T-bone steak or the like.

As disclosed in FIGS. 2 and 3, an inner housing 190 is located withinouter chamber 170 and is secured in place by bolts 191. The innerhousing 190 has a unitary housing wall 192 which presents a conicalouter surface 193 with an apex 194 and defines an inner chamber 200. Theinner housing 190 and the inner chamber 200 are radially symmetricalabout an axis which is coaxial with the outer chamber 170 and the inletpipes 30,40 axes. Inner chamber 200 includes a cylindrical portion 201which provides an opening into the inner chamber 200 for interconnectionwith inlet pipe 30. The inner chamber 200 tapers from the cylindricalportion 201 to form a frustoconical portion 202. The inner housing wall192 includes three openings 203, permitting interconnecting attachmentof three extrusion tubes 210 therein. The openings 203, and thereby theextrusion tubes 210, are radially symmetrically spaced around acircumference of the inner housing 190 and permit access to thefrustoconical portion 202 of inner chamber 200. The extrusion tubes 210extend at right angles to and are radially symmetrical about the axis ofthe inner housing.

The extrusion tubes 210 each include a tube wall 211 having an innerchamber connecting end 212 and an open terminal end 213. The innerchamber connecting ends 212 are angled so as not to disturb extrudateflow in the frustoconical portion 202 of inner chamber 200. The terminalends 213 of each tube are cooperatively aligned with an extrusionorifice 80 so that an inner substance may be extruded from the terminalend 213 into orifices 80.

The terminal end 213 of extrusion tubes 2105 have an outer diameter lessthan the frustoconical inner orifice opening 185, such that an annulus220 is formed, which permits the outer extrudate to flowcircumferentially around the inner extrudate and then extrude togetherthrough each extrusion orifice 80. To assist flow through the annulus220, the terminal end 213 of extrusion tubes 210 presents a taperedouter surface 214.

In practice, a first extrudable dough is flowed from a first extruderthrough inlet pipe 40 in the direction of arrow O (FIG. 2). Theextrudable dough then flows into and symmetrically fills the outerchamber 170. The extrudable dough flows around the inner housing 190 andtubes 210. In the meantime, a second extrudable dough is flowed from asecond extruder through inlet pipe 30 in the direction of arrow I. Thesecond extrudable dough then flows into and fills the inner chamber 200.Flow of the second extrudable dough continues from the inner chamber 200symmetrically through each of the extrusion tubes 210 and into theextrusion orifices 80.

The first extrudable dough is flowed simultaneously through the annuli220 joining the two doughs. The joined extrudable doughs are thencoextruded through the orifices 80 as a continuous center-filled body.

Blades 110 then cut the continuous body into desired product lengths, asdescribed above.

It should be appreciated that significant aspects of the above-describedstructures are symmetrical so that the path through which the first andsecond extrudable doughs flow from the extruders to each of the orifices80 is substantially symmetrical and equal. In practice, it is found thatthe manifold 10 produces continuous bodies at each orifice 80 which areuniform without the need of valves or other adjustments. This is not tosay that the flow rates from the extruders are not varied to get thedesired flow of either the first or the second extrudable dough. Rather,an object of the present invention is to provide equal distribution andflow rate of extrudable dough between each of the extrusion orifices 80regardless of conditions, such as extruder flow rate.

With respect to symmetry, the inlet pipe 30, the inlet pipe 40, outerhousing 170, and inner housing 190 are all coaxially aligned. Conicalouter surface 193 of inner housing 190 has an apex 194 which is alsocoaxially aligned with the inlet pipe 40. The coaxial apex 194 and theconical surface 193 are believed to assist in the uniform distributionof the first extrudable dough throughout the inner chamber 170 and inturn to the extrusion orifices 80.

Liners 230, made of a non-stick material such as ULTEM 1000™, areoptionally provided on one side of the manifold housing end walls 150and 160 to line the outer chamber 170 to assist flow of the firstextrudable dough.

FIG. 4 discloses a multiple-orifice manifold 300 which is an alternateembodiment of the invention. The manifold 300 is a modification ofmanifold 10 and, as such, like reference numerals are used for likecomponents. Manifold 300 differs from manifold 10 primarily in that thethree extrusion orifices 80 extend through outer housing end wall 160,thus, presenting a planar outer extrusion surface 310 as opposed to thecylindrical outer extrusion surface 70 and extrusion wall 140 ofmanifold 10. Accordingly, three extrusion tubes 320 replace extrusiontubes 210 of manifold 10. The extrusion tubes 320 are provided with aright angle bend so as to cooperatively align with the extrusionorifices 80. As with the embodiment of manifold 10, the tubes 320 extendat right angles to the inner chamber 190 axis and are radiallysymmetrically spaced from each other. The extrusion orifices 80 areequally and symmetrically spaced in housing end wall 160. In particularthe orifices 80 are radially symmetrical about the longitudinal axes ofboth inlet pipes 30, 40 and inner and outer housings 170,200.

Forming a new cutting assembly 330, a flange 340 with a diameter smallerthan the flange 100 replaces the flange 100 on the hub 90 of the cuttingassembly 50. The blades 110 are disposed on flange 340 coplanar withboth the flange 340 and the extrusion surface 310. Thus, upon rotationthe blades will cut the continuous body of center-filled dough intodesired product lengths.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention and the scope of protection is only limitedby the scope of the accompanying claims.

For example, the multiple-orifice manifold 300 disclosed in FIG. 4 maybe further modified to provide more orifices, such as orifices 80, andextend the orifices through end wall 150. Thus, the manifold 300 wouldhave orifices 80 extending through first and second walls 140, 150.This, in turn, would provide for two outer housing end walls havingplanar outer extrusion surfaces disposed directly opposite each other.In such a case, additional extrusion tubes, such as tubes 320, may beprovided to co-align with the additional orifices, or the three tubes320 may be modified to form a “Y” or “T” shape to symmetrically divideextrudate flow to all of the orifices 80.

Alternatively, a housing, such as the housing 20 shown in FIG. 3, may beshaped like a triangle, square or hexagon, etc., thereby definingmultiple extrusion walls with flat outer surfaces through which theorifices 80 may extend.

For another example, the embodiment disclosed relates to a two-layercenter-filled pet food. However, the principles of the invention may beapplied to more than two-layer products. The principles of the inventionalso apply to other than food products or solid bodies. For example, theinvention may be employed with any extrudable material, such asplastics, and may be used to make multi-layered hollow tubing or wirecoating. Also, the extrusion surfaces do not have to be planar orcircularly cylindrical, so long as the chosen shape permits symmetricalflow paths to the extrusion orifices. For example, an extrusion surface,such as 70, could have flat facets surrounding each of the threeorifices or the surface could be triangular.

What is claimed is:
 1. A method of extruding multiple continuous bodiesof radially-layered product, comprising: providing a first extruder forflowing a first extrudable substance; providing a second extruder forflowing a second extrudable substance; providing a plurality ofextrusion orifices and a plurality of means for combining the first andsecond substances so that the first substance surrounds the secondsubstance and for extruding the combined first and second substancethrough the extrusion orifices; providing a plurality of equal firstflow paths for the first substance from the first extruder to each ofthe extrusion orifices; providing a plurality of equal second flow pathsfor the second substance from the second extruder to each of theextrusion orifices; continuously flowing the first and second substancesalong the first and second flow paths; and, extruding the combined firstand second substances from the extrusion orifices.